KR102095136B1 - A method for replacing at least one authentication parameter for authenticating a secure element, and a corresponding secure element - Google Patents

Abstract

The present invention relates to a method of replacing at least one authentication parameter for authenticating a secure element cooperating with a terminal, the authentication parameter enabling an authentication system of the mobile network to authenticate the secure element, and the mobile network being a mobile network. Operated by the operator, the method comprises: A-causing the entity to store the first authentication parameter in the secure element; B-causing this entity to send a first authentication parameter to the mobile network operator so that the operator can record it in his authentication system for authenticating the secure element; C-In the event of an event, the remote platform is authorized to replace the first authentication parameter with the second authentication parameter if its authentication fails for the authentication system the next time the secure element attempts to connect to the mobile network. Sending an indicator informing the secure element to the secure element; D-upon occurrence of the event, causing the entity to send a second authentication parameter to the operator so that the operator can replace the first authentication parameter with the second authentication parameter in his authentication system; E-the secure element, so that the secure element can then authenticate itself to the mobile network using the second authentication parameter, if the secure element then fails to connect to the mobile network and if the indicator is present in the secure element It consists of replacing the first authentication parameter in the second authentication parameter.

Description

A method for replacing at least one authentication parameter for authenticating a secure element, and a corresponding secure element

The present invention relates to communication, and more particularly, to authentication of secure elements that cooperate with a terminal, such as in 2G (GSM), 3G (UMTS), 4G (LTE), IMS or CDMA networks, for example.

The secure element is typically a SIM or UICC card that can be extracted from the terminal. It can also be a so-called eUICC embedded in a terminal (soldered) or difficult to remove from it. Terminals are typically cell phones, smart phones, PDAs, and the like.

When connecting to a communication network, the secure element must authenticate itself. Authentication is the result of the calculation of the challenge transmitted from the network to the UICC, from the secure element to the operator's back-end infrastructure of the mobile communication network (3GPP or 3GPP2 HLR and 3GPP AuC for 2G / 3G / 4G networks, and 3GPP2 Ac for CDMA networks). It consists of sending, this challenge being calculated at least thanks to the authentication parameters stored in the secure memory of the secure element. This result is the SRES calculated by the A3 algorithm at the level of the security factor in a 2G, 3G or 4G network, for example, thanks to the secret key Ki.

The secret key Ki configures the authentication parameters and is stored in the secure element during the personalization phase of this secure element, for example in the building of the manufacturer of the secure element (personalization process). The secret key Ki is also sent by the manufacturer to the mobile network operator (MNO) in a so-called output file. The output file is a function of the algorithm used by the MNO and the secure element for authentication purposes, and contains the secret key Ki and other parameters used by the MNO to authenticate the secure element. The MNO stores this output file in his backend infrastructure at subscription provisioning time so that the security element can authenticate the security element when it tries to connect to the MNO's network (HLR is provisioned with some data contained in the output file) ). This mechanism exists in 2G networks that only authenticate the secure element, but also in 3G or 4G networks where mutual authentications are realized.

When the security element personalization center delivers the security element to the MNO, an output file is generated in his factories and provided to the MNO over the Internet (via a secure channel). Among other information, this output file contains network authentication secrets (IMSI, Ki, etc.). Hereinafter, it is considered that at least one authentication secret is transmitted to the MNO, and this authentication secret is hereinafter referred to as an authentication parameter.

The problem is that thieves can steal output files by compromising the security of the Internet connection between the secure element personalizer and the MNO. Output files may be stolen at the level of the MNO's network. As soon as the output file is corrupted, it is possible for an attacker to spy on network exchanges and listen to voice calls or data exchanges. This leads to privacy issues, and when theft is publicly disclosed, it leads to the MNO's churn under the initiative of the end user who lost his trust in the MNO.

MNOs do not have the ability to know if security elements have been compromised, and if so, what has been compromised. As a result, if they still want to provide the same level of security to their end users with regard to voice and data communications, they have no other choice but to replace their security elements today, which is a very big cost for them. . This is because if the security elements are embedded in the terminals (eUICCs), these security elements cannot be replaced (eg if they are soldered to the terminal) and the entire terminal must be replaced if they want to ensure their integrity. It represents a major concern.

In addition, some MNOs are simply interested in having the ability to update authentication parameters of their security elements in a secure way, as a precaution, or to provide very specific services to some specific customers (VIP, politicians, government offices, etc.). It can be.

The authentication parameters used to open secure communication between the connected device and the MNO network are provisioned in two places:

-Through the secure element (during factory personalization / production) or through the Remote Personalization System (RPS) method, for example when downloading the full subscription to the secure element via OTA;

-To the MNO backend infrastructure (MNO's authentication system); More precisely on 3GPP or 3GPP2 HLR and 3GPP AuC for 2G / 3G / 4G networks, and 3GPP2 Ac for CDMA networks (thanks to the output files provided by the security element manufacturer / personalizer, at subscription provisioning time).

Authentication of the connected terminal (or secure element) can only occur if the set of parameters are the same (shared secrets) in the secure element and in the HLR / AuC / Ac.

In order to update the authentication parameters, it is necessary to update both entities synchronously and in real time, HLR / AuC / Ac. Otherwise, the connected device will no longer be able to authenticate to the network. However, this synchronous update is difficult to perform because the HLR / AuC / Ac and OTA servers (generally capable of performing OTA updates of SIM cards or security elements) are not located in the same area of the MNO backend infrastructure. very complicated. Such systems are deployed at different security levels, without the possibility of establishing direct links.

Also, the OTA protocol used to update SIM cards is:

-Requires OTA keys that may have been compromised;

-For some of those commonly used protocols (SMS), it does not provide sufficient reliability for the success of the update campaign.

As a result, you get an updated HLR / AuC / Ac, but the risk of getting an unupdated security element can be high. If that happens, the authentication parameters are simply unavailable and the connected device will no longer be able to connect to the network using this secure element. By updating the secure element (eg SIM card), the end user will be able to return to the MNO network.

This results in a very bad user experience (much worse than having a damaged SIM) because the end user can no longer use his connected device and need to contact the MNO or go to a retail store. The result may be an increase in the effect of disenrollment for MNOs.

The problem detailed above can also be applied to security elements (cards or embedded cards) and other servers to be updated synchronously, IMS authentication, GBA authentication, EAP-SIM authentication, and the like.

Therefore, the technical problem to be solved is that both the security element and the HLR / AuC / Ac servers can be updated without introducing any exploitable backdoor to the attacker in a very secure manner, without any risk of parameter asynchronous.

The present invention proposes a solution that performs an over-the-air (OTA) update of authentication parameters of security elements deployed in the field.

The solution is achieved by replacing at least one authentication parameter for authenticating a secure element that cooperates with a terminal, the authentication parameter allowing the authentication system of the mobile network to authenticate the secure element, and the mobile network Operated by a mobile network operator, this method:

A-causing the entity to store a first authentication parameter in the secure element;

B-causing this entity to send the first authentication parameter to the mobile network operator so that the operator can record it in its authentication system for authenticating the secure element;

C-upon occurrence of the event, the remote platform replaces the first authentication parameter with a second authentication parameter if its authentication to the authentication system fails the next time the secure element attempts to connect to the mobile network Sending an indicator to the security element indicating to the security element that it is authorized to do so;

D-upon occurrence of the event, causing the entity to send a second authentication parameter to the operator so that the operator can replace the first authentication parameter in the authentication system with the second authentication parameter;

E-then if the secure element fails to connect to the mobile network and if the indicator is present in the secure element, the secure element authenticates itself to the mobile network using the second authentication parameter. In order to be able to do so, the security element is configured to replace the first authentication parameter with the second authentication parameter.

In a first embodiment, the method consists of storing a plurality of authentication parameters in the secure element, the first authentication parameter being placed at the beginning of a list of authentication parameters, and step E is retrieving the first authentication parameter. It consists of replacing with a second authentication parameter, and the second authentication parameter is ranked immediately after the first authentication parameter in the list.

In a second embodiment, the method consists of storing a plurality of authentication parameters in the secure element, and step C is the second to be used the next time an attempt is made to connect to the mobile network if the indicator is present. It is further configured to transmit a rank in the list of authentication parameters to the secure element.

In a third embodiment, the second authentication parameter is calculated by the secure element based on a seed and a diversifier.

The diversifier may be transmitted to the secure element during step C.

Preferably, the second authentication parameter is calculated by the secure element based on the first authentication parameter and the identifier of the secure element.

Advantageously, the entity is the manufacturer of the security element.

In a preferred embodiment, the indicator is transmitted to the secure element via the mobile network operator.

The secure element is preferably constructed by any of the following elements:

-Subscriber Identification Module (SIM) card;

-Universal Integrated Circuit Card (UICC); or

-Embedded UICC (eUICC).

The present invention also relates to a secure element comprising a first authentication parameter for a mobile network, the first authentication parameter enabling the authentication system of the mobile network to authenticate the secure element, the secure element comprising: Includes:

-Inform the security element that it is authorized to replace the first authentication parameter with the second authentication parameter if its authentication fails for the authentication system the next time the secure element attempts to connect to the mobile network Means for storing an indicator;

-If the secure element fails to connect to the mobile network using the first authentication parameter, the secure element may use the second authentication parameter to authenticate itself to the mobile network. Means for replacing one authentication parameter with the second authentication parameter-the means for replacing is activated when the indicator is present in the secure element.

Preferably, the secure element includes a memory that stores the second authentication parameter.

Advantageously, this memory stores a plurality of authentication parameters.

Alternatively, the secure element comprises computing means for calculating the second authentication parameter after receiving the indicator.

The invention will be better understood in connection with the description of the unique drawings showing the steps in the method of the invention in which the secure element provider provides the secure elements to the MNO.
In this figure, three steps are described:

The first step consists in generating several sets of authentication parameters for the same secure element. Here, three sets K1, K2 and K3 are created and loaded into the secure memory of the secure element. However, only one set K1 is active, ie, the secure element can authenticate itself to the network by using only set K1. The sets K2 and K3 are "sleeping" sets and can be activated later (described below). The key set contains at least an authentication parameter, for example the key Ki. The output file OF-K1 containing the key set K1 is sent to the MNO and can be provisioned in the MNO's backend elements as usual. The other sets K2 and K3 remain secure in the issuer's factory, for example in the KMS and are not sent to the MNO. Therefore, these sets are kept secret and cannot be damaged by third parties (attackers).

When a user of a terminal comprising a security element comprising set K1 attempts to connect to the MNO's network, he will be authenticated as usual, since the K1 set exists and is activated in the security element and in the network (authentication system).

The second stage occurs when an event occurs. This event could be, for example:

-The issuer or MNO feels that a security problem has occurred (set K1 of parameters may have been stolen or damaged).

-The MNO determines that a security campaign should be initiated that changes the set of parameters (eg once a month).

-MNO wants to perform some preventive update of the parameters in the security elements;

-The VIP or government office requests new sets of parameters for security reasons.

In this second step, upon request of the MNO or at the initiative of the issuer, the issuer delivers the new output file to the MNO. This output file was securely stored on the issuer's premises (eg KMS / HSM) and should not be corrupted. The new output file (OF-K2) contains the key set K2 already included in the security element. The key set K3 is kept confidential on the issuer's premises.

MNOs can then launch campaigns against security elements that need to change their key sets. In the figure, the security element with the key set K1 must change the authentication key K1. To do this, a simple OTA campaign should be started. It consists of setting an indicator (flag) on the secure element, by a remote platform (eg, OTA platform, belonging to the issuer or MNO). The remote platform is authorized to replace the current (first) authentication parameter with the second authentication parameter if its authentication fails for the authentication system the next time the secure element attempts to connect to the mobile network. Sends an indicator to the security element. The secure element continues to keep key set K1 active (replacement of K1 has not yet been performed), but is ready to replace it with a new one.

For the security elements that the campaign has reached, MNO uses his usual provisioning mechanism to provision new key sets in his backend infrastructure. The MNO replaces the first authentication parameter with the second authentication parameter in its authentication system. When new authentication for the network is performed by the connected device, the authentication parameters will fail because the active parameters on the secure elements are still the initial ones, while the active parameters on the MNO backend are new ones.

So the third step consists in detecting that the secure element is unable to connect to the network: his authentication has failed. In this case, the security element checks whether a flag is present. If the flag is not present, the security element continues to authenticate using the key set K1. If the flag is present, the secure element is the first authentication parameter so that the secure element can authenticate itself to the mobile network using the second authentication parameter K2 (K2 is active at the network level and at the security element level). Replace K1 with the second authentication parameter K2. If authentication is successful using K2, the flag is reset and a new authentication is started again. It is also possible to attempt authentication on the network using the second parameter K2, and if successful, replace K1 with K2 and reset the flag.

Later, it will be possible to replace the key set K2 with the key set K3 using the same mechanism.

More specifically, the authentication process begins by sending a challenge (random + this random cryptographic signature + other data) by the network to the connected device. The security element is responsible for authenticating the network by first checking the cryptographic signature. If the active parameters are not good ones, the recalculation of the cryptographic signature will not match: authentication will fail on the security element side. However, as part of the present invention, if the replacement mechanism was previously activated, the secure element may immediately attempt to calculate the cryptographic signature using another of its provisioned parameters. If the new cryptographic signature calculation matches, the set of parameters used becomes a new active set and the authentication process can continue with those parameters: the secure element will then send a challenge that will allow the network to authenticate the secure element. (For mutual authentication).

In the above description, the key sets are stored in the list, the first authentication parameter K1 is placed at the beginning of this list (automatically activated) and it (if the flag is active and authentication fails) is the first authentication parameter in the list. It is replaced with the second authentication parameter K2 immediately after K1. The K3 authentication parameter is ranked # 3 in the list.

Such a list may include, for example, 12 different authentication parameters (after K12, K1 is selected again, so that the MNO can change the authentication parameters once a month, and no authentication parameter is 1 month per year. The list is cycled so that it is not used in excess of).

Upon occurrence of the event (step 2), if an indicator is present, a security element indicates which authentication parameter he is authorized to use later by indicating a rank in the list of authentication parameters to be used the next time an attempt is made to connect to the mobile network. It is also possible to mark on. This means that as part of the OTA command sent to the secure element to activate the replacement mechanism, an identifier of a new set of parameters to be used may be provided.

Another way to handle authentication parameters is to use the seed (master key) and diversifier to calculate the authentication parameters to be used in case of authentication failure, where the seed is installed in a secure element during manufacturing / personalization and the diversifier is in the middle of the campaign. It is transmitted to the secure element.

The alternative consists in calculating the second authentication parameter at the level of the secure element based on the first authentication parameter and the identifier of the secure element, for example its integrated circuit card identifier (ICCID).

The entity that stores authentication parameters in the secure element and sends them to the MNO is preferably the manufacturer (or personalization plant) of the secure element. However, in the case of remote personalization of the secure element, another entity, for example the operator of the server managing the secure elements, can realize these functions. The operator can establish links with multiple MNOs to download a complete subscription profile to secure elements already in the field. Thus, the end user can request the download of keys, programs and data from different MNOs, so he can have multiple subscriptions (perhaps obtained from different MNOs) on his device.

To be interoperable, an indicator (flag) sent to the secure element can be sent to the MNO by the manufacturer of the secure element. In this case, it is important that the flags are protected by information (keys) not included in the output file (because this information may have been previously hacked by an attacker). Therefore, this key must also be kept secret by the manufacturer's KMS / HSM. The flag can be transmitted via OTA or Wifi in an OTA command, for example.

The method according to the invention applies, among them, to any security elements:

-SIM cards

-UICCs cards

-Embedded UICCs (eUICCs)

The present invention introduces a new OTA order for activation of the replacement mechanism. Since this may open up a new attack vector for security elements, the present invention also includes additional security protection:

-In the security element at the time of manufacture, a key will be provisioned, named "Replacement Mechanism Protection Key". This key will never leave the security factor issuer factory or personalization center.

-If the MNO requests delivery of a set of new parameters, the secure element issuer factory is also responsible for calculating the payload of the OTA command (used in the OTA campaign mentioned above) to be sent to the secure element. This OTA command is protected by the "replacement mechanism protection key" of the security element.

Upon receipt of the OTA command, the secure element will verify the payload using the "Replace Mechanism Protection Key" provisioned at the time of manufacture. If the verification is not successful, the replacement mechanism remains inactive.

-"Failed payload check counter" can be implemented to increase the security level: the security element can be muted when the number of remaining available failed payload checks reaches zero.

As variants of the invention:

-To improve the reliability of the OTA protocol, it is also possible for the secure element to send a message (for example, a Mobile Originated SMS, also called "MO SMS") to the server to confirm the activation of the replacement mechanism. MO SMS is only sent if the SMS received by the card is authenticated (according to the final ETSI releases 102.226 and 3GPP 31.115, to avoid "premium number attacks").

-The set of parameters can be used multiple times during the life of the SIM card (the number of changes in the set of parameters is unlimited), or reuse of the set of parameters can be blocked / limited (if changing the set of parameters, the previous set Can be considered "burned", which means that it can no longer be used, if a set of N parameters was provisioned to the SIM card at the time of manufacture, up to N-1 changes can be performed. Means there).

-The set of parameters can be stored as individual values in the secure element issuer factory: The set of N parameters is safely stored per card. This results in the important number of data being protected and stored in the secure element issuer manufacturer backend system. The set of parameters may be interactive by storing only "primary seed values" that can be used to dynamically recalculate individual sets of parameters as required.

On the secure element, instead of provisioning the entire set of parameters to the factory, a similar “basic seed values” approach can be used: a set of on-board keys / parameters can be performed when the replacement mechanism is executed. For any diversification algorithm, it is also necessary for both parties to know about the diversifier: this diversifier is part of the payload of the OTA command (used in the OTA campaign mentioned above) to be sent to the SE. You can.

When "basic seed values" are used both on the server and client side, the number of sets of parameters that can be used in the card can be infinite (every time the replacement mechanism is triggered, a new set is created on demand). Note that.

The advantages of the present invention are as follows:

-The secret / key is not transmitted over the air.

-There is no automatic / real-time server interaction between the OTA system and the MNO backend (HLR / AuC / Ac).

-Real-time synchronization between server systems is not required.

-Very simple OTA campaign

-Any network generation is valid (3GPP or 3GPP2 network)

-There is no risk of connection loss during the parameter change process.

The present invention also relates to a security element comprising a first authentication parameter for a mobile network, the first authentication parameter enabling the authentication system of the mobile network to authenticate the security element, the security element comprising: Includes:

-Inform the security element that it is authorized to replace the first authentication parameter with the second authentication parameter if its authentication fails for the authentication system the next time the secure element attempts to connect to the mobile network Means for storing an indicator;

-If the secure element fails to connect to the mobile network using the first authentication parameter, the secure element may use the second authentication parameter to authenticate itself to the mobile network. Means for replacing one authentication parameter with the second authentication parameter-the means for replacing is activated when the indicator is present in the secure element.

The secure element according to the invention preferably comprises a memory for storing the second authentication parameter and advantageously a plurality of authentication parameters. The first parameter of rank 1 may be stored in dedicated memory or in the same memory as the parameters of higher rankings.

Alternatively, the secure element comprises computing means for calculating the second authentication parameter after receiving the aforementioned indicator.

Claims (13)

A method of replacing at least one authentication parameter for authenticating a secure element that cooperates with a terminal, wherein the authentication parameter enables an authentication system of a mobile network to authenticate the secure element, and the mobile network is operated by a mobile network operator. Operated-,
A-causing the entity to store a first authentication parameter in the secure element;
B-causing the entity to send the first authentication parameter to the mobile network operator, so that the operator can record it in his authentication system for authenticating the secure element;
C-second authentication of the first authentication parameter to the remote platform upon occurrence of the event, if its authentication to the authentication system fails the next time the secure element attempts to connect to the mobile network Sending an indicator to the security element indicating to the security element that it is authorized to replace it with a parameter;
D-upon occurrence of the event, causing the entity to send a second authentication parameter to the operator, allowing the operator to replace the first authentication parameter with the second authentication parameter in his authentication system step;
E-in the event of a subsequent failure of the secure element to connect to the mobile network and when the indicator is present in the secure element, the secure element can authenticate itself to the mobile network by the second authentication parameter. So that the security element replaces the first authentication parameter with the second authentication parameter
The method consisting of. According to claim 1,
The method consists of storing a plurality of authentication parameters in the secure element, the first authentication parameter being placed at the beginning of a list of authentication parameters, and during step E, the method is configured to remove the first authentication parameter from the first authentication parameter. 2, wherein the second authentication parameter is ranked immediately after the first authentication parameter in the list. According to claim 1,
The method consists of storing a plurality of authentication parameters in the secure element, and step C, if the indicator is present, ranks in the list of second authentication parameters to be used in the next attempt to connect to the mobile network. And transmitting it to the secure element. According to claim 1,
And the second authentication parameter is calculated by the secure element based on a seed and a diversifier. According to claim 4,
Wherein the diversifier is transmitted to the secure element during step C. According to claim 1,
And the second authentication parameter is calculated by the secure element based on the first authentication parameter and the identifier of the secure element. The method according to any one of claims 1 to 6,
Wherein the entity is the manufacturer of the secure element. According to claim 1,
And the indicator is transmitted to the secure element via the mobile network operator. The method according to any one of claims 1 to 6 or 8,
The security elements include:
A subscriber identity module (SIM) card;
Universal Integrated Circuit Card (UICC); or
Embedded UICC (eUICC)
Method consisting of any one of. As a security element comprising a first authentication parameter for a mobile network, wherein the first authentication parameter enables the authentication system of the mobile network to authenticate the security element-,
Informing the security element that it is authorized to replace the first authentication parameter with the second authentication parameter if its authentication to the authentication system fails the next time the secure element attempts to connect to the mobile network. Means for storing an indicator; And
If the secure element fails to connect to the mobile network using the first authentication parameter, the first authentication parameter is such that the secure element can authenticate itself to the mobile network with the second authentication parameter. Means for replacing the second authentication parameter with the second authentication parameter, the means for replacing being activated when the indicator is present in the secure element-
Security element comprising a. The method of claim 10,
The security element comprises a memory for storing the second authentication parameter. The method of claim 11,
The memory is a secure element characterized in that it stores a plurality of authentication parameters. The method of claim 10,
And the security element comprises calculation means for calculating the second authentication parameter after receiving the indicator.

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